What does a rationalist do for Christmas (or whatever analogue is going on around you at this time)? Stay at home and grumble, "Bah, humbug! Stop having-fun-for-bad-reasons, and did you know that Láadan has a single word for that concept?"?
Attempting to light a candle instead, I am giving my teenaged nephew, who was into science but is now into history, "Guns, Germs and Steel", which combines both. Someone else (I haven't decided who) is getting "The Atheist's Guide To Christmas" which has chapters by Richard Dawkins, Ben Goldacre, Simon Singh, and the like.
What are you doing for Christmas?